1. Field of the Invention
Embodiments of the present invention generally relate to a linear electric motor for an artificial lift system.
2. Description of the Related Art
Crude oil is often produced using a sucker rod pump driven by a surface mounted pumping jack. However, this system of artificial lift is very inefficient. Not only are the pumps and the sucker rod connecting the downhole pump to the pumping jack very expensive, but they also suffer from several technical problems.
One of the major problems is that, since most wells are not straight, the sucker rod usually rubs against the tubing in a number of places. This problem is even more severe in wells that are intentionally directionally drilled and whose deviation from perfect straightness can be quite large. Not only does this wear the sucker rod and the tubing, necessitating the costly replacement of both, but the friction between the sucker rod and the tubing wastes energy and requires that more powerful motors be used to operate the pumping jack. In cases where the sucker rod completely wears through the tubing, there is also the problem of losing production from the production tubing back into the well casing. This rubbing action also causes the tubing to move up and down with the rods, necessitating the installation of tubing anchors.
Other problems associated with present sucker rod pumping systems are breakage of the bridle line connecting the pumping jack head to the polish rod, freezing of engine fluids in cold weather, pollution from engine exhaust, and leaks around the wellhead associated with the moving seal between the polish rod and the stuffing box.